Joint for concrete slabs



ly 1940- E. H. GEYER ET AL, 2,208,454

JOINT FOR CONCRETE SLABS Filed July :5, 1937 2 Sheets-Sheet 1 I .ErrzeaZJi. Ge er I I V fivenzwqs 35 Y He July 16, 1940. E. H. GEYER ET AL. 2,208,454

- JOINT FOR CONCRETE SLABS Filed July 5, 1937 2 Sheets-Sheet. 2

mmlml Patented July 16,1940

JUNlTED STATES PATENT OFFICE JOINT FOR CONCRETE spans Ernest H. Geyer and Henry A. Taubens'ee, Chicago; Ill.

Application July 3, 1937, Serial No. .151,8 18

21 Claims.

of laterally spaced, one piece metallic sleeves which are adapted to extend between and to have their end portions bonded respectively to the slabs and have the central portions thereof weakened so that they will 'readily distendor.

1 expand or rupture and hence permit the end portionsto move to and from one another in response to expansion and contraction of the slabs; and (2) dowel rods which are mounted 20 slidably in,and extend across the central portions one slab to the other.

One object of the invention is to provide a joint of this type which is an improvement upon, and has certain inherent advantages over, previously designed joints of the same'general character and for the same purpose by reason of the fact that it includes tubular stress reducers which are mounted on and grip'frictionally the end portions of the sleeves and serve notvonly to reinforce such portions of the sleeves ut also to increase the bearing surfaces between the joint and the slabs.

Another object of the invention is to provide a joint of the last mentioned character in which, the stress reducers for reinforcing the end portions of the sleeves. and increasing the bearing surfaces between the joint and the slabs have laterally projecting wings whereby they become bonded to the slabs after pouring and setting of the latter.

Another object of the invention is to provide A a joint of .the type and c aracter under consideration which includes in addition to the stress reducers; a novel form or type of frame structure 115 which serves to support the sleeve, dowel and stress reducer assemblies in their operative position during pouring of the concrete in connec- 'tion with slab formation.

r I A further object of the invention is to provide 56 a iointof the last mentioned character-in which the frame structure comprises laterally spaced stake-like members which extend verticallywhen intheir operative position and have the upper ends thereof shaped to interlock with the wings iI'of-the stressireducers and their lower-ends of, the sleeves, and serve to transmit load from frame structure serves to support the sleeve,

' bodying the invention;

pointed for embedment in the sub-grade over which the slabs are formed. i

A still further object of the invention is to provide a joint which may be produced more cheaply and assembled more readily than the 5 joints which are shown in and form the subject niatter of United States patent applications Serial Nos.'47,734 and 69,026, filed respectively, November' 1, 1935, and March 16, 1936, and is characterized by the fact that the sleeves and dowel bars are materially shorter and are spaced farther apart than the sleeves" and dowel bars of the joints of said applications without im-' pairment of the efliciency of the joint as a whole Other objects of the invention and the various advantages and characteristics of the'present joint for concrete will be apparent from a consideration of the following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly defined by claims at the conclusion hereof.

In the drawings which accompany and form a part of this specification or disclosure and in which like numerals of reference denote corresponding parts throughout the several views:

Figure 1' is a fragmentary perspective of an expansion type joint embodying the invention, illustrating in detail the manner in which the 'dowel rod and stress reducer assemblies prior to pouring the concrete in connection with formation of the slabs; V

Figure 2 is a side elevational view of one of the. aforementioned assemblies of the expansion Figure 3 is Figure 2;

Figure 4 is an enlarged longitudinal vertical" ;sectional view of the assembly of Figures 2 and 3; 40 Figure 5 is a sectional view taken on the line 55 of Figure 4 and showing in detail the construction and design of the caps for closing the epds of the sleeves; Figure 6 is a transverse sectional. view taken on the line 66 of Figure 4 and disclosing in dean end view of the assembly of tall the arrangement and design of the interlock- Figured is a perspectiveview of oneof the stress reducers of the contraction type joint;

Figure 9 is an enlarged transverse sectional stress reducers which are used in connection with the plane of weakness type of joint.

The joint which is shown in Figures 1 to 6, inclusive, constitutes one embodiment of the m vention. It is essentially an expansion joint and is shownin connection with a pairof adjoining roadway forming. slabs S on a'sub-grade G. The slabs are formed of concrete and, as shown in Figure 2, they are spaced slightly apart and have a strip-like filler F therebetween. This filler is formed of any suitable resilientor elastic material and extends from thesub-grade G to a point slightly beneath the top faces of the slabs.

The joint operates to transmit load from one of sleeves at the other side of .the slabsto the other and permits the slabs to expand and contract as the result of changes in temperature or climatic conditions. It is adapted to be assembled and placed'across the sub-grade G before pouring of the concrete in connection with formation of the slabs S and comprises as the main or essential parts thereof a'set ofsleeves I 3, dowel rods M in the sleeves, stress reducers l5 around the end'portions of the sleeves, anda fabricated steelframe structure [6 for supporting the assemblies of sleeves, 'dowel rods, and stress reducers.

The sleeves are formed of any suitable sheet metal and are slit longitudinally. They :are maintained in a horizontal plane and in laterally spaced relation by the frame structure l6 during pouring of the concrete in connection with the formation of the slabs S and project through and are centrally positioned with respect to the striplike filler F. The end portions of the sleeves at one side of the filler are adapted for embedment in oneof the slabs S and the end portions of the I the fillerare adapted for embedment in the other slab. The outer faces of the sleeves are coated with zinc or any vent flow of concrete other like material which chemically reacts with concrete in such manner that it bonds itself thereto. As the result of the coatings the end portions at one side of the flllerand the end portions of the sleeves at the other side of the filler become bonded respectively to the slabs-S after. pouring and'setting of the. latter.- ,The sleeves l3 are preferably of substantial uniform diameter om one end-thereof to the other. The central portions of the sleeves, that is, the portions within the filler F embody slots l1. These slots so weaken the central portions of the sleeves that such portions distend or rupture or .expand in response to movement of the slabs S to and from one another sion orcontraction. Preferablyv the slots II in the central portion of each sleeve are arranged ln -an annular series. By having the slots ll in the central portions of the sleeves, that is, the portions within thefiller, the filler serves to preinto the sleeves via this slots during formation of the slabs. The ends) the sleeves are closed against the inflow of as the result of expan- .bers which are movable and complemental lower lindrical central parts stress reducers.

concrete by way of sheet metal caps l8. These caps are cup-shaped and comprise imperforate disk-like cross-walls l9, outw'ardlyfiared annular'side walls 20, and radially and outwardly projecting annular flanges 2| at the outer ends of the side walls. The side walls 20 of the caps tit within the ends of the sleeves and embody outwardly extending projections 22 which grip frictionally the inner faces of the outer ends of the sleeves and serve to hold the caps in place. The flanges 2| abut against the end edges of the sleeves and form lap' joints whereby inflow of concrete between the caps and ends of the sleeves is eifectively prevented. As soonas the slotted central portions of the sleeves'rupture or break the end portions become separated from one another and form at the ends of the dowel rods separate or independent sleeve memto and from one another in response to expansion and contraction of the .two slabs. I

The dowel rods 14 are formed of steel and fit snugly and slidably in the sleeves l3. They are centrally positioned in and extend across the central portions of the sleeves and are of such length that the ends thereof terminate slightly inwards of the caps Ill. The sleeves are filled with graphite or any other suitable lubricant so that the dowel rods are free to slide relatively thereto and serve whereby the load of one slab S is transferred to the other slab. In order to hold temporarily the dowel rods in centered relation with the sleeves and thus to prevent sliding of the rods from one end to the other during transportation of the joint from the place of manufacture to the place of installation, instruck projections'23 are formed on the outer extremities of theend portions of the sleeves. These projections, as shown in Figure 4, are adapted to bear against the ends of the dowel rods and thus hold the rods in a centered position with respect to the sleeves. In assembling the joint thedowel rods M are inserted into placein the sleeves. During insertion of the'rods the sleeves, due to the, longi-' tudinal slits therein, spring laterally to a small extent and permit the rods to pass by the projections 23 at the dowel. rod entering ends of the sleeves. Upon complete insertion of the rods in the sleeves, the sleeves spring back into place and form lapped joints along the-slits thereof whereby inflow of concrete through said slits is prevented. 1

The stress reducers l5 aretubular and are mounted on the inner parts of the end portions of the sleeves I 3. They serve to reinforce such parts of the sleeves and to surfaces between the joint and the slabs S. As shown in Figures l, 2, 3 and 6 of the drawings, the stress reducers comprise upp'er sections 24 sections 25. The upper sections embody semi-cylindrical parts 26 and laterally extending wing parts 21.- The semicylindricalparts 26 are adapted to overliethe inner parts of the end portions of the sleeves and the wing parts 21 are formed integrally with said; parts 26 and are positioned diametrically opposite one another. The lower sections 25 are adapted to underlie the inner parts of the end portionsof the sleeves and comprise semi-cy- 28 and laterally extending wing parts 29. The wing parts 29 underlie and are welded or othepwise fixedly secured to the wing parts 21 of the upper sections 24 of th as load transfer members 65 increase the bearing Preferably the upper and lower 75 sections are in the form of metal stampings. The inner faces of the semi-cylindrical parts of the stress reducer sections define cylindrical sockets 30 which are slightly smaller in diameter than the external diameter of the sleeves. As a result of this, when,the stress reducers are driven into place they grip frictionally the sleeves and are thus maintained in place. Each sleeve carries two stress reducers. The stress reducers atone side of the filler F are adapted for embedment in and become bonded to one of the stress reducers are approximately one-fourth as long as the sleeves and, as shown in Figures 2- and 4, extend from the filler F to points substantially half way the distance between the filler and the caps l8 at the ends of the sleeves. In

order to prevent collapse of the filler F during assembly of the joint and pouring of the concrete in connection with the formation of the slabs S,

the sleeves are provided with pairs of square washers 3|, which are mounted on the central portions of the sleeves and fit against the side faces of the filler. They are formed of sheet metal or any other suitable material and are held in clamped relation with the filler by means of the stress reducers l5 which, as shown in Figures 2 and 4, are arranged in abutting relation with the washers. The stress reducers at one side of the filler are held against outward axial I or longitudinal displacement with respect to the sleeve end portions on which they are mounted by means of out-struck projections 32 which, as shown in Figure 4, are arranged to abut against the outer endsof such stress reducers. At the place where the joint is manufactured or fabricated the dowel rods are inserted into the sleeves, ashereinafter described, and then the sleeves, after being charged or fllledwith graphite or other suitable lubricant, are closed by'inserting the caps l8 into place.. After insertion of the dowel rods into the sleeves the stress reducers for embedment in one of the slabs are driven onto the sleeves until they abut against the projections 32. The joint is shipped to the place of assembly or installation without first driving into place the stress reducers for embedment in the other slab, At the place of assembly or installation, the washers for one face of the flller F are' mounted on the sleeve end portions'wh'ich have no-stress reducers and are slid axially or lengthwise of the sleeves until they abut against the inner ends of the stress reducers on the other end portions of the sleeves. Thereafter the,

'sleevevend portions without the stress reducers are slid or shifted through thefiller F until the sleeves are arrested as a result of the contact of the mounted washers with the adjacent faceof the filler. After manipulating the sleeves in this manner the other washers are mounted on the sleeve end portions without the stress reducers and are slid inwardly into-an abutment with the other face of the filler. Thereafter the re-c mainder of the stress reducers are driven onto the sleeves until they abut with the last mentioned washers and cause clamping of both sets of washers against the filler. 'whenthe sleeves, dowel rods and stress reducers are in their fully or completely assembled position, the stress reducers because of contact with the washers hold the sleeves at right angles to the filler and maintain them in parallel relation.

The frame structure it serves to support the filler F together with the assemblies of sleeves.

dowel rods, and stress reducers during pouring.

of the concrete for the slabs S. It is of unitary design and consists of a pair of laterally spaced, substantially horizontally extending elongated members 33 and 31, a set of stake-like upstanding members 35, and a set of stake-like upstanding members 36. The elongated members 33 and 34 are formed of comparatively heavy steel wire and are positionedon oppositesides of, and in parallel relation with, the filler F. They are adapted to rest on the sub-grade G and operate to limit downward movement of the stake-like members 35 and '36 and also to hold or maintain such members in spaced relation and in their upright position. The upstanding members 35 correspond in number ,to the sleeves l3 and have the central portions thereof welded to the member 33. They arespaced a slight distance from the filler F and embody pointed lower ends for embedment in the sub-grade. The upper ends of the stake-like members 35 project through holes 31 in certain of the wing parts of the stress reducers thereabove and are provided with pairs of oppositely extending shoulder forming ears 38 for supporting the-stress reducers with which the members 35 are associated. The up standing members 36' correspond in number to the sleeves l3 and have their central portions welded to the elongated member 34. They have pointed lower ends for embedment in the subgrade and are-spaced outwardly from the filler F. Thevupper ends of the members 36 extend through holes 39 in the stress reducers l5 thereabove and have shoulder forming cars 43. for supportingsaid reducers.- The ears 40 are similar to and are horizontally aligned with the ears lower ends of the upstanding stake-like mem bers 35 and 36 are forced downwards into the sub grade until the members 33 and 34 strike.

against the top face of saidsub-grade. After so positioning the members of the frame structure; the strip-like filler F is placed in an upstanding position between and in parallel rela- 'tion with the members 34 and 35.

After so positioning the filler the stress reducers Ii above the upstanding members 35 are moved downwards so as .to bring the upper ends of said members 35 through the holes 31 and the wings at one side of said stress reducers into abutment, with the ears 33. -At theconclusion of such manipulation 9f the stress reducers above the members 33' the other stress reducers are correspondingly manipulated so as to' bring the upper ends of the members 3.6 through the holes .33 and the wing parts at one side of such other stress reducersinto abutment-with the shoulder "forming ears 30 on the upper ends of said upstanding members 38. when all of the stress reducers are in place the extreme upper ends of the members 35 and 36 are bent over by way of a hammer or like tool so as to secure the stress'reducers and such members in locked re- 5' lation. The upstanding members 35 are located at one side of the sleeves l3 and the members 36 are laterally offset with respect to the membars .35 and are located at the other side of the sleeves. By so arranging the members 35and 10 36, the stress reducers at one side of the filler are supported on one side and the stress reducers at the other side of the filler are supported at the other or opposite side and hence the joint as a whole is exceptionally rigid. After 15 assembly and proper placement of the joint, the slabs S are formed by pouring concrete into the spaces at the sides of the filler. Upon hardening of the concrete the sleeve end portions and the stress reducers at one side of the filler be- 20 come bonded to one of the slabs, as previously pointed out, and the other sleeve end portions and stress reducers become bonded to the other slab. When the slabs expand as a result of increase in temperature the sleeve .end portions 25 at oneside of the strip move toward the other sleeve end portionsand stress reducers and the filler becomes compressed. Upon contraction of the slabs the sleeve end portions and stress reducers at opposite sides of the filler move away 30 from one another and the central portions of the sleeves distend or expand. Due to the fact that the dowel rods are slidably'mounted in the sleeve I3, the slabs regardless of the extent of their expansion or contraction are operatively 35 connected together and the load from one slab is transmitted or transferred to the other slab. By reason of the fact \that the joint includes stress reducers i5 whereby there, is a material increase in bearing surfaces between the con :40 crete and the joint as a whole, it is possible to space the assemblies of sleeves, dowel rods and stress reducers quite far apart and to use extremely short sleeves and dowel rods.

The joint which is shown in Figures 7, 8 and 9 45 of the drawings constitutes another embodiment of the invention. It is a contraction type joint and is shown in connection with a pair of adjoining roadway forming concrete slabs S and a sub-grade G beneath the slabs; The slabs S 50 are separated by an elongated horizontally extending metal plate P and are adapted in response to contraction resulting from a decrease in temperature to moveaway from one another and the plate. The plate embodies an angle iron leg pat the bottom thereof for supporting it iii an upright position with respect to the sub-grade I G and has. a sheet metal cover member p over. the top margin thereof. The cover embodies laterally extending upwardly inclined extensions for preventing water'or moisture from passing downwards between the plate P and the contiguous faces-of the slabs 'S. The joint of Figures 7 to!) inclusive functions like, and embodies the same structural features or characteristics as 35 the expansion joint of Figures 1 to 6 inclusive, and comprises as the main. or essential parts thereof, a set oflaterally spacedhorizontally'extending sheet metal longitudinally split sleeves 1 I I3. dowel rods M in the sleeves, stress reducers 70 I5 around the end portions of the sleeves, and

a fabricated steel frame structure l6 for supporting theassemblies of sleeves, dowel, rods and stress reducers. The sleeves l3 are the same as the sleeves l3 of the hereinbefore de- 75 scribed expansion joint and have slot weakened 7 central portionsand also end. caps 18. They extend through and. are centrally positioned with respect to the plate Pbetween the slabs S and are adapted after pouring and setting of the slabs S to have the end portions thereof become bonded to the slabs for longitudinal movement therewith.

The dowel rods I 4' fit slidably in the sleeves 13 and serve to transmit load from one of the slabs S'- to the other slab.

The stress reducers l5 serve the same purpose as the stress reducers l5 of the expansion joint of Figures 1 .to 6 inclusive, although they differ from said stress reducers l5 as far as construction or design is concerned. They are mounted on the inner parts of the end portions of the sleeves l3 and are in the form of one-piece longitudinally split steel tubes. The internal diameter of the stress reducers I5 is slightly less than the external diameter of the sleeves and hence the stress reducers I5 grip the sleeves yieldingly and frictionally when driven into place. The inner ends of the stress reducers l5 abut against square washers 3| on the central portions of the'sleeves and hold such washers in abuting relation with the plate P. The outer endsof the reducers are split longitudinally and then circumferentially to form. wing parts 21. The latter are bent outwardly and extend horizontally and have holes 3'! in the central portions thereof.

The frame structure [6 is exactly the same as the frame structure l6of the aforementioned expansion joint and embodies elongated horizontally extending members 33 and 34 and upstanding stake-like members 35 and 36 The upstanding members 35 and 36 arewelded to the members 33* and34 respectively and are provided inwardly of the upper extremities thereof with pairs of oppositely facing shoulder forming ears. The extreme upper ends of the members 35 and 36 project through theholes 3'! in the wing parts 21 of the stress reducers 15 and are bent over at right angles so as to secure the stress reducers in connected relation with the frame structure I 6. reducers at one side of the plate P have the wing parts 21 thereof projecting in one direction and the stress reducers at the other side of the plate have their wing parts arranged to project in the opposite direction, as shown in Figure 7. When the slabs S contract the sleeve end portions and the stress reducers atone side of the plate P move away from the othersleeve end portions and stress reducers and slide with respect to the dowel rods I l.

The stress l2, constitutes another embodiment of the invention. It isa so-called. plane of weakness joint and is shown in connection with a pair of adjoining roadway forming slabs S" and a subgrade G." beneath the slabs. The slabs S" have a composition'filler F" between the upper portions thereof. The latter is held in place during pouring of the concrete as well understood in the art and so weakens'the concrete that when a vehicle runs thereover or a load is placed thereon, it splits or breaks in substantially a .vertical plane, along the filler F" and thus forms the two slabs. The split or break extends from the filler F" to' the bottom of the slabs and formation of the slabs S".

same as the sleeves l6 and i6 of the expansion and contraction type joints and have slots (not traction joints in that" it serves to transfer or transmit load from one slab to the other and at the same time permits theslabs to move one relatively to the other. It is in the nature of a unit and consists of a set of longitudinally split sheet metal sleeves I3 solid steel dowel rods shown) in the central portions thereof. The end portions of the sleeves i6 are closed at the outer extremities thereof by caps l8 and become bonded to the concrete after formation of the slabs S".

The dowel rods M fit snugly and slidably in the sleeves 13 and serve as the load transfer form wing parts 21 members.

The stress reducers l fit snugly around the inner parts of the end portions of the sleeves Iii and are formed of helically wound metallic strips. There are two stress reducers for each sleeve of the joint, as shown in Figure 10. The inner ends of the stress reducers l5 on each sleeve terminate at the split or break between the slabs S" and are arranged in abutting relation so that they cover the sleeve slots and prevent the flow of concrete therethrough. The stress reducers at one side of the split become bonded to one of the slabs upon hardening of the concrete and the other stress reducers become bonded to the other slab. The outer ends of the stress reducers l5 project laterally and These wings are adapted to become interlocked with the concrete and have vertical holes 31 therethrough.

The frame structure l6 is the same as the frame structures of the hereinbefore described expansion and contraction joints and includes upstanding stake-like members 35 and 36*, the upper ends of which have pairs of outwardly extending shoulder. forming ears and project through the vertical holes 31 in the wing parts 21 at the outer ends of the stress reducers.

Whereas the joint of Figures 1 to 6,'inclusive, and the joints of Figures '7 to 9, inclusive, and Figures to 12, inclusive, have ben described as comprising sleeves around the dowel rods, it is to be understood that in certain instances the sleeves may be omitted and the stress reducers applied to the ends of the dowel rods. It is also.

to be understood that the invention is not restricted to the details set forth, since these may be modified within the scope of the appended claims, without departing from the spirit and scope of the invention.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent is:

1. A joint for adjoining concrete slabs, com prising in combination a series of laterally spaced substantially parallel dowel rods adapted to extend across the space between the slabs and to have their ends project into the slabs for load pouring oi. the slabs, and stress reducers of less length than the sleeve members mounted on parts of said sleeve members and adapted for embedment in the slabs and to move with the latter and said members, said stress reducers consisting of stamped metal semi-cylindrical sections with laterally extending fiat full length side wings and separately formed stamped metal compiemental semi-cylindrical sections with laterally extending flat full length wings in lapped relation with, and secured to, the wings of the first mentioned sections, and being of such internal diameter that they grip the sleeve members with inward pressure and remain tenaciously in the various positions to which they may be manually slid prior to pouring of the concrete for the slabs. 2. A joint for adjoining concrete slabs, com

prising a series of laterally spaced substantially parallel dowel rods adapted to extend across the .-space between the slabs and to have their ends project into the slabs for load transfer purposes, cylindrical sleeve members mounted on and completely encasing the ends of the dowel rods and adapted to move with the slabs in response to expansion or contraction-of the latter and having the inner ends thereof connected together in a temporary manner prior to pouring of the slabs, and wing equipped stress reducers-of less length than the sleeve members and in the form of iongitudinally split, resilient metal tubes, fitting .around and gripping frictionally and with inward pressure parts of the sleeve-members and adapted for embedment in the slabs and to move with the latter and said members.

3. A joint for adjoining concrete slabs, comprising a series of laterally spaced substantially parallel dowel rods adapted to extend across the space between the slabs and to have their ends project into the slabs for load transfer purposes, cylindrical sleeve members mounted on and completely encasing the ends of the dowel rods and adapted to move with the slabs in response to expansion or contraction of the latter and having the inner ends thereof connected together in a temporary manner prior to pouring, of the slabs,-.

and separately formed tubular stress reducers of less length than the sleeve members and inthe form of helically wound, resilient metal strips, fitting around and engaging frictionally and with inward pressure parts of the sleeve members and adapted for embedment in the slabs and to move with the latterand said members. 7

4. In combination with a pair of adjoining concrete slabs, a joint for'the slabs comprisingia series of laterally spaced parallel dowel rods having the central portions thereof extending across the space between the slabs and their ends projecting into the slabs for load transfer purposes, cylindrical metallic sleeve members slidably mounted on the ends of the dowel rods and adapted to move with the slabs in response to expansion or contraction thereof, and tubular stress reducers in the form of helically wound metallic strips, fitting around and gripping frictionally the inner parts of the sleeve members, adapted to move with the slabs 'and said'members, and having their outer ends bent outwards to provide laterally'projecting wings in interlocked relation with the slabs.

5. A joint for adjoining concrete slabs, comprising in combination a series, of laterally spacedhaving their central portions weakened so that side wings and complementalsemi-cylindrical.

sections with laterally extending wings in lapped or abutting relation with, and secured to, the

wings of the first mentioned sections.

6.,Ajoint for adjoining concrete slabs, comprising in combination a series of laterally spaced substantially parallel one-piece metallic sleeves adapted to extend between, and have the end'portions thereof become bonded respectively to, the slabs and having thecentral portions weakened so that they will distend or rupture and hence permit the end portions to move \t9 and from one another in-response'to expansion and contraction of the slabs,'dowel rods mounted slidably on the sleeves and extending across thecentral portions thereof, and stress reducers in the form of longitudinally split metallic tubes fitting around and gripping frictionally and with inward pressure parts of the end portions of the sleeves and adapted for embedment in the slabs and to move with the latter and said end portions.

7. A joint for adjoining concrete slabs, comprising in combination a series of laterally spaced substantiallyparallel one-piece metallic sleeves adapted toextend between, and have the endportions thereof become bonded respectively to, the slabs and having the central portions weakened so that they will distend or rupture and hence permit the end portions to move to and from one another in response to expansion and contraction of the slabs, dowel rodsmounted slidably on the sleeves and extending across the central portions thereof, and tubular stress reducers in the form of helically wound metallic. strips, fitting around and gripping frictionally parts of the end portions of the sleeves and adapted for embedment in the slabs and to move with the latter and said end portions.

8. A joint for adjoining concrete'sl abs, com-- prising in combination a series of laterally spaced substantially parallel dowel ,rods adapted to extend across the space between the slabs'and to have their ends project into the slabs for load transfer purposes, and stress reducers in the form of resilient metal tubes, fitting around and movable relatively to the ends; of the'dowel rods,

- prising in combination a seri adapted for embedment in the slabs and to move with the latter ,in'response to expansion or contraction thereof, and having the outer ends thereof slit and bentoutwards to forms-laterally extending wings. A

9. A jointior adjoining-concrete slabs, comof laterally spaced substantially parallel dowel rods adapted to extend across the space between the slabs and to have their ends project into the slabsfor load- 4 transfer purposes, tubular stress reducers in the 7 ,-form of helically wound metallic strips, extending around and movable relatively to theends of the dowel rods at oneside of the joint and adapt-,-

ed for embedment in the contiguous slab, and to move with the latter in response-to expansion and oontractionthereof, and separately formed tubular elements in the form of helically wound inereducers.

tallic strips, extending around and movable relaprising in combination a series of laterally spaced substantially parallel dowel rods adapted to extend across the space between the slabs and to have their ends project into the slabs forload transfer purposes, and tubular elements in the form -of helically wound metallic strips, extending around and movable relatively to the ends of the dowel rods, adapted for embedment in the slabs and to move with the latterin response to expansion or contraction thereof, and having the oi ter ends thereof bent outwards to form lat-' erally projecting wings. i

11. A joint for adjoining concrete slabs on a sub-grade, comprising in combination a; series of laterally spaced substantially parallel dowel rods adapted to extend across the space between the slabs and to have their ends project into the slabs for load transfer purposes, sleeve members slidably mounted on the ends of the dowelrods and adapted to move with the slabs in response to expansion and contraction of the latter, tubular stress reducers on the inner parts of the sleeve members adapted for embedment in the slabs and to move with the latter and said members and embodying laterally extending wings, and a frame structure for supporting the joint during pouring of theconcrete for the slabs embodying upstanding stake-like members having the" lower ends thereof pointed for embedment in the sub-grade and their upper ends projecting through holes in and interlocked with the wings of the stress 12. A joint for adjoining concrete slabs on asub-grade, comprising in combination a series of laterally spaced substantially parallel dowel rods adapted to extend across the space between the slabs and to have their ends project into the slabs for loadtransfer purposes. tubular elements extending around and movablerelatively to the ends of the dowel rods, adapted for embedment in p the slabs and to move with the latter in response to expansion or contraction thereof, and provided with laterally extending wings, and means for supporting the joint during pouring of the concrete for the slabs adapted to rest on the sub grade and embodying upstanding members having the upper ends thereof in interlocked relation with the wings.

18. A joint for adjoining concrete slabs, comprising in combination a series of laterally spaced substantially parallel dowel rods adapted to'ex tend across the space between the slabs and to have their endsproject into the slabs for load transfer purposes, and tubular elements in the vform of.helically wound metallic strips, extending around and movable relatively to the ends of the dowel rods at one side of the joint, adapted for embedment in thecontiguous slab and to move with the latter in response to expansion and contraction thereof, and having certain ends of the I strips thereof bent outwardly to formlaterally projecting wings.

14. A joint for a pair of adjoining concrete'IO slabs, comprising a dividing element adapted to fit within the space between the slabs, a plurality of laterally spaced parallel cross members adapted to have the ends thereof project into the slabs and having their central portions extending; 7,5

transversely through the element, and tubular resilient metal stress reducers with laterally extending wings for slab interlocking purposes,

mounted on portions of the ends of said cross members and adapted for embedment in the slabs and to move with the latter in response to 'con' traction thereof, said stress reducers being being adapted in connection with assembly of the joint to be shifted inwardly intoa position wherein the filler element is clamped between them and the cross members are thus held in substantially fixed relation with said element.

15. A joint for a pair of adjoining concrete slabs, comprising a flller element adapted to fit within and seal the space between the slabs, a

plurality of laterally spaced parallel cylindrical cross members adapted to have the ends thereof project into the slabs and having their central portions extending transversely through the element, and tubular stress reducers on portions of the ends of said'cross members adapted for embedment in the slabs and to move with the latter in response to contraction thereof and composed of semicylindrical stamped resilient metal sections with integral laterally extending full length side wings and complemental semi-cylindrical stamped resilient metal sections with integral laterally extending full length wings in lapped or abutting relation with, and secured to, the wings of the first mentioned sections, said stress reducers being formed originally with their internal diameter less than the diameter of the cross members in order that when they are mounted on the end portions of the cross members prior to pouring of the concrete for the slabs ,they grip said portions with inward pressure and remain tenaciously in place, and being adapted in connection with assembly of the joint to be shifted or slid inwardly into a position wherein the. filler element is clamped between them and the cross members are thus held in substantially fixed relation with said element.

16; A joint for adjoining concrete slabs, comprising in combination a series of laterally spacedparallel cross members adapted to extend across the space between the slabs and to have their ends project into the slabs, and tubular resilientmetal stress reducers mounted on portions'of the ends of said cross members and adapted for embedment in the slabs and to move with the latter in response to expansion or contraction thereof,

said stress reducers having laterally extending wings for interlocking with the slabs and being formed originally with their interiors of less width than the cross members in order that when they ate mounted on said portions of the ends of thecross members prior to pouring of the concrete in connection with formation of the slabs tend across'the space between the slabs and to have their ends project into the slabs, and tubular stress reducers mounted on portions of the ends of said cross members that are at one side .of the joint and adapted for embedment. in the contigu- ,ous slab and to move with thelatter in response 7 18. A joint for a pair of adjoining concrete slabs comprising a series of laterally spaced parallel cross members adapted to extend across the space between the slabs and have their ends project into the slabs, and tubular resilient stress reducers of originally less internal-width than the width of the cross members adapted for embedment in the concrete and mounted on portions of the cross members, said stress reducers being resiliently held in place during pouring of the concrete for the slabs and embodying side wingsfor interlocking with the concrete,

19. A joint for a pair of adjoining concrete slabs, comprising a series of laterally spaced par-' allel one piece sleeves adapted to extend between, and have the end portions thereof become bonded to the slabs .and having their central portions weakened so that they willreadily rupture and permit the end portions to move from and to each other in res nse to contraction and expansion of the sla s, load transfer dowel rods mounted slidably in the sleeves and extending across the central portions thereof, and tubular resilient metal stress reducers of less length than the end portions of the sleeves, mounted on parts of said end portions and adapted for embedment into which" they may be manually slid or shifted prior to pouring of the concrete in connection with formation of the slabs 20. A joint fora pair of adjoining concrete slabs comprising a dividing element adapted to fit within the space between the slabs, aplurality 'of laterallyspaced parallel cross members adapted to have the ends thereof project into the slabs and having their central portions extending transversely through the element, and tubular metallic stress reducers with laterally extending wings for slab interlocking purposes mounted on portions of the ends of said cross members and adapted for embedment in the slabs and to move with thelatter in response to expansion or contraction thereof, said stress reducers having resilient parts for gripping said end portions of the cross members directly andwith sufllcient inward pressure that said stress reducers remain tenaciouslyin place on said portions of the cross concrete for the slabs, and being adapted in connection with assembly of, the joint to be shifted or slidinwardly into aposition wherein the element is clamped between them and the cross members are thus held in flxedrelation with said element. I j I 21. A joint for a pair of adjoining concrete slabs comprising a series of laterally spaced parallel cross members adapted to extend across the members prior to and during pouring of the space between the slabs and have their ends project into the slabs, and tubular stress reducers adapted for embedment in the concrete and mounted on portions of the cross members,

said stress reducers being provided with side I wings for interlocking with the concrete and em bodying resilient parts for gripping said portions of the cross members directly and with suflicient inward pressure to hold the stress reducers in place during pouring of the concrete for the slabs.

ERNEST H. GEY ER. HENRY A. TAUBENSEE. 

